Prior art systems for removing volatile organic contaminants from particulate material such as soil, sludge or the like conventionally perform a heating step that removes the contaminants from the particulate material. This heating can be used to remove hydrocarbons such as gasoline, fuel oil or kerosine etc. Such heating removes the organic contaminants as gas emissions which must be treated in order to prevent contamination of the atmosphere. These gas emissions have conventionally been treated by combustion or incineration that oxidizes the organics as well as by wet scrubbing and the use of activated carbon. Such conventional treatment of the gas emissions must be performed on a relatively large volume flow which necessarily results in substantial costs.
One prior art system for removing volatile organic contaminants from particulate material is disclosed by U.S. Pat. No. 4,738,206 Noland. The system disclosed by the Noland patent incorporates mixing of a portion of the emissions with fresh air for flow through a combustion chamber to a oil heater that performs the heating of the particulate material. Such heating is performed on a heat exchange medium which is fed to a screw having hollow flights such that rotation of the screw moves the particulate material and also provides its heating. The combustion gases are fed over the particulate material as it is heated and conveyed in a counterflow manner.